Table 1. Nine broad-scale biodiversity processes, and their spatial surrogates, in the Gouritz planning domain. All spatial boundaries were matched to the closest planning unit boundary. The processes form the corridor network. Further details can be obtained from Lombard et al. (2004).

Process

Spatial component

Method of identification

Primary GIS layers

P1

Migration and exchange across macroclimatic
gradients between inland and coastal biotas, north and south
biotas, and upland-lowland biotas, providing dispersal
opportunities in the event of environmental change; maintenance
of fresh water flow, water quality and quantity, flood control,
and estuarine integrity

Riverine corridors

All planning units that intersect with the
North-South Gouritz River main stem, and its two sources in
the north, the Dwyka and Gamka Rivers

Rivers

P2 and P4

Geographic diversification of plant and animal
lineages; migration of biota, especially far-ranging animals
such as birds and leopards; maintenance of natural fire regimes
(many fynbos species are fire-driven); generation and maintenance
of perennial fresh water for the lowlands (the mountains are
important water catchment regions to retain surface and underground
water sources)

Geographic and ecological diversification
of plant and animal lineages (there is a high turnover of
species within and among these heterogeneous patches); seed
dispersal (quartz patches and associated succulent vegetation
are hotspots of botanical diversity and occur as stepping-stones
along a northwest to southeast gradient in the western Little
Karoo, providing a gradient of changing species - they are
not continuous, but are linked to one another via processes
such as seed dispersal, for example, by leopard tortoises)

Quartz patches and associated succulent vegetation

Delineated on base maps at expert workshops

Quartz patches (Driver at al. 2003)

P5

Maintenance of dispersal and diversification
of the distinctive coastal biota, most of which are restricted
to this narrow, linear zone; inland movement of marine sands
and associated soil development within coastal dunes and sand
movement corridors; maintenance of plant succession processes
associated with the primary dune systems; coastal wetlands
performing flood control and water filtration thereby enhancing
estuarine integrity; intact coastal regions provide protection
against storm events and sea-level rise in response to global
warming

Coastal corridors

Coastal vegetation types within a two km coastal
corridor from the west to the east of the planning domain.

Coastline
Vegetation types

P6

Representation of the biological gradients,
i.e., north-south, upland-lowland, and east-west macroclimatic gradients,
within the biogeographically distinct Gouritz water catchment
(intact gradients promote the long-term maintenance of ecological
and evolutionary processes such as migration, diversification,
and adaptation to climate change along drainage basins that
support thicket vegetation).

Plant and animal dispersal associated with
the biodiversity of the Renosterveld of the coastal forelands
(this is not catered for in any of the other corridors - the
vegetation of the region is highly fragmented, mainly by wheat
fields, but many small patches remain along the hilltops and
these enable seasonal migration of some fauna and act as important
refugia for geophytes and small succulent plants, many of
which are highly localized endemics)

Plant and animal dispersal associated with
the biodiversity of the lowlands; disturbance created by,
for example, grysbok and bushbuck movement and feeding, and
by molerats tunnelling – these processes are important
for the regeneration of fynbos plants; pollination by, for
example, nectarivores, which need to be able to fly across
ecologically intact areas.

Lowland vegetation

Lowland and coastal vegetation, and vegetation
associated with east-west bands of geology, and north-south
gradients along river courses.